For people who rely on augmentative and alternative communication (AAC), assistive technology (AT) is available that can at least partially alleviate this disability. However, the selection and application of AAC systems often is more of an art than a science. This project consists of the definition, development, and evaluation of a language activity monitor (LAM) in two configurations. One is an aftermarket add-on device that can be used with any existing AAC system with an RS-232c serial output. The other is the incorporation of the LAM function into an existing AAC system. The LAM will record language events (one or more letters or words) generated by the system and add a time stamp with a one second resolution. This data can be uploaded to a computer for editing and analysis. The implications of this work will fall into three areas: research, outcomes measurement, and clinical intervention. Research will be able to be based on real communication by people who actually rely on AAC. Clinical intervention can be based on objective information that includes actual use of the AAC system. PROPOSED COMMERCIAL APPLICATION The Language Activity Monitor will be made commercially available and offered until the market demand dissipates. The LAM function, based on a proposed standard recording protocol, will be built into future AAC systems. Phase II will include the development of editing and analysis software products and clinical intervetion strategies.